1. Field of the Invention
The present invention relates to an antenna, and more particularly, to a multi-frequency antenna for transmitting Wi-Fi and WiMax wireless signals.
2. Description of the Related Art
Due to the developments in wireless communication technology, many electronic devices, such as notebooks and mobile phones, now incorporate wireless communication technologies to transmit information. Besides mobile communication devices, like notebooks and mobile phones, desktop computers can also be used to transmit signals through wireless communication technologies. To receive and transmit signals, the prior art has disclosed an antenna for electromagnetic radiation for these electronic devices.
In modern wireless communication technologies, the Wi-Fi (Wireless Fidelity) antenna is currently the most important tool for transmitting signals. Therefore the Wi-Fi antenna is built into all kinds of wireless communication products. However, due to the progress in the development of wireless communication technologies, the WiMax (Worldwide Interoperability for Microwave Access) antenna will become main stream in the future. Yet the operation frequency of the Wi-Fi antenna and the WiMax antenna are different. The Wi-Fi antenna's operation frequency is about 2.4 GHz and 5 GHz. The WiMax antenna's operation frequency is about 2.3 GHz, 3.3 GHz and 5 GHz.
Please refer to FIG. 1A. FIG. 1A shows a prior art technology disclosed in U.S. Pat. No. 6,861,986. An antenna 90 comprises a radiating element 91, a connecting element 92 and a grounding element 93. The connecting element 92 has a first end 921 and a second end 922. Furthermore, the first end 921 of the connecting element 92 is connected to the radiating element 91, and the second end 922 is connected to the grounding element 93.
Next, please refer to FIG. 1B. FIG. 1B shows the voltage standing wave ratio (VSWR) at different frequencies according to the prior art antenna 90 shown in FIG. 1A. As shown in FIG. 1B, the prior art antenna 90 only transmits at about 2.5 GHz and 5 GHz. Therefore, in the prior art a WiMax signal can only be transmitted by mounting a WiMax antenna in addition to a Wi-Fi antenna. This increases manufacturing costs and also occupies additional space within the communication products.
Thus, it is desirable to provide a multi-frequency antenna to mitigate and/or obviate the aforementioned problems.